The present invention relates to the wine making industry and to the removal of the residue of wine fermentation remaining in a processing tank after the fermented wine is removed. More particularly, to an apparatus and method for the automated removal of the remainder of grape skins, stems and other material, generally referred to as pomace, from the fermentation tank after the completion of fermentation, wherein the method of removal of the wine pomace minimizes the maceration of the pomace so as to permit the extraction of wine product retained in the pomace without imparting undesirable compounds from the pomace to the wine product.
During fermentation of wine, the remains of grape skin and vine material, known as pomace, settles to the bottom of the fermentation tank forming a thick, fibrous sludge. After the fermented wine is drained from the fermentation tank leaving the pomace in the tank, a significant amount of fermented wine is retained within the pomace. The pomace is discarded; however, recovery of the retained fermented wine is economically desirable. Recovering the retained wine from the pomace has long presented the wine industry with difficulties as undesirable compounds are typically released from the pomace and departed to the wine tainting the wine in an undesirable manner when the pomace is mechanically disturbed. Prior to the present invention, mechanical processes to remove the pomace typically macerate the pomace thus releasing the undesirable compounds. The present invention minimizes the mechanical disturbance to the wine pomace therefore also minimizing the release of the undesirable compounds.
Prior to the present invention, many manual and mechanically assisted techniques have been employed to remove pomace from the fermentation tank. The principal mechanically assisted technique for pomace extraction is the use of pressurized fermented wine hosed into the pomace so as to suspend the pomace fragments in the wine thereby permitting the flushing of the mixture of wine and pomace from the tank. The mixture is pumped and filleted to a wine press where the wine is squeezed from the mixture. This flushing and pumping technique sufficiently disturbs the pomace to release unacceptable amounts of undesirable compounds into the wine.
More typically, pomace is removed manually by shoveling. Fermentation tanks are typically cylindrically shaped closed tanks with an entry portal on the side of the tank tangent to the bottom. The bottom of the tank is typically shallowly pitched towards the entry portal so as to assist the drainage. After fermentation, the pomace forms a 3 to 5 foot matting in the bottom of the tank, usually covering the entry portal. Typically, and most commonly, a worker opens the entry portal, exposing wine pomace settled against the entry portal. Using a shovel or similar implement, the worker digs into the impacted pomace until an entry path can be made into the fermentation tank. The worker then enters the fermentation tank through the entry portal. The pomace is removed by shoveling the pomace along with the remaining retained wine through the entry portal and transferring the material into receptacles for subsequent draining and pressing. Gravity draining and light pressing of the fermented wine from the manually removed pomace typically imparts acceptably low levels of undesirable compounds to the fermented wine. This shoveling extraction process is labor intensive, time consuming and raises safety issues for the worker.
As manual removal of pomace requires a worker to enter a closed tank, CO2 asphyxiation during pomace removal is not uncommon in the industry. CO2 is a byproduct of the fermentation process and continues to be generated by fermentation within the pomace.
There has been a need for an apparatus and method to remove the wine retaining pomace that avoids these disadvantages. The present invention fulfills this need, and further provides related advantages.